The construction of drain assemblies in tile shower installations has conventionally involved the use of a well-known, two-piece drain to which a shower pan is sealably attached beneath a mortar bed. The term “two-piece” drain is used because this type of drain typically includes at least two components that compress and seal the shower pan between the two components to secure the shower pan to the drain. Tile is typically applied over the mortar bed and the mortar bed serves as a conduit to direct water to the shower pan and the water is drained over the shower pan and into a waste drain through weep holes formed in sides of the two-piece drain.
Recently, a different type of assembly has become popular for use in shower floors that involves the use of a bonded (or bondable) waterproof membrane. In general, a bondable waterproof membrane bonds directly to the mortar bed (or a suitable equivalent) and protects the mortar bed (and any underlying structure such as the subfloor) from contact with moisture from the shower. The incorporation of bondable waterproof membranes in floor drain installations has generally required that drain fittings other than the conventional two-piece drains be developed. This is because conventional two-piece floor drains were designed to connect to shower pan liners below the mortar bed and so did not provide for a secure, watertight connection to bondable waterproof membranes at the top of the drain assembly.
For this reason, drain fittings having so-called “integrated bonding flanges” have been developed for use with bonded waterproof membranes. A typical integrated bonding flange installation is illustrated in FIGS. 1A and 1B. Because it is imperative that the bondable waterproof membrane form a watertight seal with the integrated bonding flange drain, these types of drains are typically provided with an upper bonding flange that has a relatively large surface area, such as that shown in FIG. 1A, to provide maximum surface area for adherence to the bondable waterproof membrane.
While the integrated bonding flange system has proved popular with tile installers (or “tile setters”), there exists a sometimes significant time delay between the point in time that a plumber installs the plumbing for the integrated bonding flange drain and the point in time at which a tile installer completes the tile shower installation utilizing the integrated bonding flange drain. As such, it is sometimes difficult for the plumber to properly ascertain the height at which the various components of the drainage system should be installed to ensure that the tile setter can properly complete the installation. In addition, as the integrated bonding flange drain protrudes some distance above the subfloor (it is generally seated on a bed of mortar, or equivalent structure, by the tile setter), the integrated bonding flange drain can be exposed to potentially damaging forces during the intervening days, weeks or months after the plumber installs the drainage components and before the tile setter completes the installation.
Thus, while the bonded waterproof membrane shower system is increasing in popularity, problems have arisen relating to the discontinuity in time between the work performed by the plumber and the finished tile installation performed by the tile setter.